Unregister

Part of speech: verb

Definitions

1. To remove from an official list or database, or to cancel an existing enrollment or registration
2. To take something or someone off an official record or enrollment list
3. To cancel the status of being formally recorded in a directory or register

Etymology: "Unregister" is a plain formation: the prefix "un-" attached to the verb "register." English "un-" is an old native element, descended from Old English "on-" (which is itself related to "and-," meaning "against" or "back"), and it was used in English as a reversing prefix, so "unregister" is simply "to undo a registering." The base verb "register" comes from Latin "registrum," a record book, so the sense of the whole word is to strike a name off the list it was once written into. The word belongs to a large group of reversing verbs like "unlock," "untie," and "unbind," which English builds freely from its own prefix. It is a compound formed in English rather than a word inherited from an older language, so its history lies in the combination of two familiar parts.